Adjustable holding mechanism



April 7, 1964 J. E. MARTENS 3,127,783

'ADJUSTABLE HOLDING MECHANISM Filed June 8, 1961 3 Sheets-Sheet 1 JACK E. MARTENS m uZ/L A TTOR NE Y J. E. MARTENS 3,127,783

ADJUSTABLE HOLDING MECHANISM 3 Sheets-Sheet 2 mm. m: E 5 Q: Q: m: E E :1 N9 3 8. mm. 3 :1 m9 m: m: 9

0. m mm mm mm m we mm @m Ch 0 v v I i I i I I! I in I April 7, 1964 Filed June 8, 1961 L ow mm @m -53 ow \\WK W m mm 8; w 2

INVEN TOR. JACK E. MARTENS ATTORNEY April 7, 1964 J. E. MARTENS 3,127,783

ADJUSTABLE HOLDING MECHANISM Filed June 8, 1961 3 Sheets-Sheet 3 INVENTOR. JACK 5. MA RTENS M MZ/L ATTORNEY United States Patent Ofiice 3,127,783 Patented Apr. 7, 1964 3,127,783 ADJUSTABLE H LDING MEQHANIdll/I Jack E. Martens, Gary, Ind, assignnr to The Anderson Company, a corporation of Indiana Filed .lune 8, 1951, Ser. No. 115,694 8 Claims. tCl. 74--424.8)

This invention relates generally to adjusting mechanism and more particularly is directed to a manual positionadjusting or holding mechanism having an improved linear movement and braking device therefor. It is a continuation-in-part of my application Serial No. 79,255 filed December 29, 1960.

The invention is particularly adaptable for use in chairs having reclining backs or in beds having tiltable portions, and for this reason is described within such a setting; however, the mechanism has other uses and is in no way meant to be limited by this present disclosed application in its usage.

Many types of linear actuators or positioning devices for use with beds or reclining backs of chairs are available on the market which employ, for instance, a rack and detent, nut and actuated screw, rod and clamping device, or a hydraulic system. In many instances these devices cause a great deal of difiiculty and are, therefore, the subject of constant improvement and refinement. Quite often when failure occurs in the ratchet and detent of the clamping type adjuster device, the back of the chair or movable portion of the bed is locked in the position of failure or movable only to the completely reclined position and cannot be held in a raised position until repaired. In the hydraulic type actuators, fluid leakage is a constant problem not only because of damage to fabrics and other physical surroundings but once the hydraulic fluid has escaped from the cylinder, control is lost and the chair back or bed will creep to a reclined or lowered position.

In seats on buses, automobiles and aircraft, for example, it is desirable to have a seat with a back portion which is adjustable to any angular position. For use on beds, for instance, the adjuster is so positioned to hold the tiltable portions in a fixed position. The holding mechanism of the adjuster can be manually released, and the weight of the human body shifted to adjust the tiltable bed frame structure to the desired position.

It is, therefore, a principal object of this invention to overcome the disadvantages of the prior art and to provide an improved position-holding mechanism.

Another object of this invention is to provide a posi tion-holding mechanism employing a screw-nut arrangement having an improved braking or holding device associated therewith.

Another object of this invention is to provide a positionholding mechanism of an extenuator type wherein is provided a braking or holding device and means to control said braking device.

An object of this invention is to provide a holding mechanism, the extension or contracting of which is releasably braked in both directions.

Yet another object of this inventon is to provide a positionholding mechanism that is simple in construction and operation.

Other objects of this invention will become apparent from the following description hereinafter set forth taken in conjunction with the accompanying drawings.

In the drawings:

FIGURE 1 is a schematic showing of the adjuster in use with a reclining or adjustable bed in a horizontal or lowered position.

FIGURE 2 is a schematic showing of the adjuster in use with the bed in a raised position.

FIGURE 3 is a cross-sectional view of one form of the adjuster.

FIGURE 4 is a sectional View taken along line 4-4 of FIGURE 3.

FIGURE 5 is a cross-sectional view of another form of the adjuster.

FIGURES 6 and 7 are exploded views of FIGURE 5, wherein FIGURE 7 is a continuation of the right-hand end of FIGURE 6.

In referring to the drawings, like reference numerals designate similar elements or parts throughout the several views. In FIGURES 1 and 2 the numeral 10 designates an adjustable bed having sections 12, 14 and 16 positionable to a desired contour by releasing the adjustor brake and the proper positioning of the weight of the human body. Once the desired contour or position is obtained, adjustor 2%., in its normally braked position, will hold the section in relative position.

While the present disclosure is shown in use with a bed, it is to be understood that its use is not so limited but has utility in other arrangements as well.

It can be seen that with the sections 12, 14 and 16 arranged the way th-ey are shown in FIGURES 1 and 2, that if the adjuster 20 is fixedly maintained. at a predetermined selected linear extended or retracted position, the sections making up the bed frame will be retained in the desired fixed position. Whenever it is desired that the position of the bed be changed, it is only necessary to manually release a brake means on the adjustor, and manually move the sections to the desired location and permit the brake to resume its holding arrangement.

FIGURE 3 is a longitudinal cross-sectional view of one form of my adjuster. An elongate outer casing 26 of tubular form has provided at one end an inturned shoulder 23 having a suitable bushing 30 which receives a second tubular member 32 in slidable telescopic relationship. The other end of outer casing 26 is provided with a pin 34 extending diametrically through and fixed thereto for the purpose of providing a means of anchoring the casing to an object to be adjusted. Pin 34 serves an additional function to be more fully described in the specification. The second tubular member 32, which is partly received within casing 26 in telescopic relationship, is provided with a pair of diametrically opposed holes 36 in its outer end for the purpose of attachment to another object to be adjusted relative to the object attached to pin 34 on the outer casing 26.

The inner end of tubular member 32, which is received within outer casing 26, is provided with an enlargement 36 which fixedly contains therein nut member 38. This nut can be of several varieties including, for example, acme thread, circulating balls, or the type shown in my US. Patent 2,924,112 or the Wise US. Patent 2,938,401. Many other types of nuts may be used provided they operate with a minimum of friction loss in cooperation with threads on a screw of appreciable axial lead.

Rotatably mounted within outer casing 26 and located within member 32 is a screw member 46 having external threads of appreciable axial lead received within the nut 38. Screw member 40 is rotatably mounted at its inner end by thrust-bearing means 53 concentrically positioned within outer casing 26. The inner end portion 42 of screw member at is provided with a reduced diameter as compared to the diameter of the threads thereon. The outer end of portion 42 is provided with threads 44 to receive a nut 56 thereon. A pair of bearing sleeves 46, 48 is received on reduced portion 42 in axial aligned relationship, and are adapted to fixedly position a washershaped annular bearing raceway 5i) therebetween. An annular bearing raceway 52, s milar to raceway 50, is secured between the other end of sleeve 48 and the shoulder 5d formed between reduced portion 42 and the threads. Raceway 5% is retained between sleeves 46, 48 whereas raceway 52 is maintained in spaced relationship thereto by an amount equal to the length of sleeve 48. Nut 56 secures bearing sleeves 46, 48 and raceways 50, 52 in axial spaced relationship on said reduced portion 42 of shaft 40 so as to rotate with said shaft 40.

The annular thrust-bearing means or block 58 is positioned inside tubular member 26 and fixed thereto by means of pins or screw devices 60. An annular hole 62 extends axially through block 58 to rotatably receive sleeve 48 on shaft 42. Positioned on either side of thrust block 58 and surrounding sleeve 48 is a pair of ball-thrust bearings 68, 68' to restrain screw member 40 against axial movement while supporting said screw 40 for rotation about its axis. Screw member 40, and the elements attached thereto, is thereby rotatably received concentrically within casing 26 in axially restrained thrust relationship.

The rest of screw member 40, extending to the right as viewed in FIGURE 3, is provided with helical threads 41 of an appreciable or steep axial lead. The threaded portion extends the full length of the screw member 40 except for the reduced portion 42. The right-hand end of the threaded portion is terminated in a guide member 70 within tubular member 32. Nut member 38 nonrotatably housed within enlargement 36 of member 32 operatively receives the screw member 40 therethrough, and cooperates with threads 41 thereon. As mentioned in this specification the nut may be of several types, but the type disclosed in US. Patents 2,924,112 and 2,938,401 has been found very satisfactory. The threads 41 are steep so that, upon a linear nonrotative axial movement of member 32 and nut 38 along screw member 40, the screw member will be caused to rotate in one direction (e.g. clockwise) within its established bearing means 68, 68'. An axial movement of nut 38 and tubular member 32 in the reverse direction will cause the screw member to rotate in the other direction (counterclockwise).

Bearing sleeve 46 which surrounds portion 42 of screw 40 has a radial flange 71 fixed therewith and protruding therefrom of a diameter less than the inside diameter of casing 26. Bonded or otherwise secured to an axial face of the flange 71 is a brake material 72 having an exposed friction surface.

Now referring to the mechanism at the other end of the adjuster in FIGURE 3, slidably received within the left end of casing 26 is a cylindrical sleeve member 73, shown in FIGURES 3 and 4, with an inturned flange portion 74 loosely surrounding sleeve 46. The outer axial end surface of the inturned flange 74 has bonded or otherwise secured thereto an annular shaped brake material 75 of high friction surface exposed adjacent brake material 72 and in mating relationship therewith. An axially extending longitudinal slot 76 is provided on diametrically opposed walls of member 73 astride aforementioned pin 34 to limit axial movement of the sleeve member 73 within and relative to casing 26. Axial movement of sleeve 73 engages or disengages brake surfaces 72, 75 thereby controlling the freedom of rotation of screw member 40 which has in effect the brake surface 72 carried thereby.

The mechanism which controls the axial position of cylindrical sleeve 73 within casing 26 Will now be described. Fixedly secured within the left end of casing 26 (FIGURES 3 and 4) is a second thrust-bearing block 76, similar to block 58, which is held in fixed position within casing 26 by pins or screw devices 77. A hole in block 76 provides a pivotal bearing surface for a shaft 79 extending therethrough. Shaft 79 protrudes beyond the outer end of casing 26, and has fixedly connected thereto a transverse handle 80 for use by the operator to pivot the shaft about its axis. A thrust bearing 83 is positioned outside bearing block 76 to restrain relative axial movement of shaft 79 inwardly, or to the right as viewed in FIGURE 3. The other end of shaft 79, remote from handle 80, is provided with a pin 84 extending transversely therethrough. Pin 84 is of a length less than the diameter of sleeve 73. The pin is adapted to be rotated with shaft 79 to bear against a cam surface 88 of cam member 87 to move the cam axially of casing 26. Said cam member 87 is fixedly secured within the end opposite inturned flange 74 of cylindrical sleeve 73 by radial pins 85. The cam 87 moves with the sleeve 73 and is adapted to slidably receive shaft 79. It is to be noted, as shown most clearly in FIGURE 4, that the right-hand end of block 87 is provided with a pair of cam surfaces 88 which are adapted to be engaged by the pin 84.

Belleville springs 89 surround shaft 79 and are positioned to bear against thrust block 76 and cam block 87 to urge cam block 87 to the right. It is readily apparent that sleeve 73, to which cam 87 is attached, will be likewise axially urged to the right carrying friction surface 75 into holding contact with surface 72 on the screw 40. From this arrangement it will be seen that screw 40 is braked against rotary movement. Movement of handle on the pivot shaft 79 will move pin 84 from the low spot of the cam 87 up the inclined surfaces 88 to move cam 87, sleeve 73 and brake surface 75 to the left. Screw 40 is now free to rotate about its axis.

In operation with an adjustable bed or chair, the adjuster is adapted to hold a desired linear distance between attachment means 34 and 36, on casing 26 and tubular member 32 respectively. Movement of the handle 80 releases the brake surface 72' whereby the axial distance between points 34, 36 may be changed by a slight axial force such as that applied by a chair back or bed portion. Once the desired position is attained, handle 80 is released and permitted to return to its normal position, and spring action again seats the brake into holding position.

In holding position, brake surfaces 72, 75 are urged into contact by the resiliency of the Belleville springs 89. Since cylindrical sleeve 73 is movable axially, but restrained from rotation by diametral pin 34, brake surfaces 75 and 72 coact to restrain screw 40 from rotation. Since screw 40 is restrained from rotation, nut 38, which is located thereon, is not free for relative axial movement therealong. It is apparent that as long as the brake surfaces 72, 75 are urged together, that the desired distance between pin 34 and hole 36 is maintained.

Pivotal movement of handle 80, in a range of 0-90 degrees, pivots shaft 79 and causes cross pin 84 to bear against cam surface 88 to move cam 87 to the left. Since cylindrical sleeve 73 and brake 75 are fixed with respect to cam 87, they too are moved to the left whereby brake Surface 75 is lifted free of brake surface 72. Screw 40 is now free for rotary movement in its thrust hearing but, of course, is restrained from any axial movement. Since screw 40 is released, an applied axial force between points 34 and 36 will move nut 38 along the screw to any position between pin 90 on screw 40 and inturned shoulder 28 on casing 26. It is apparent that once the desired position is obtained between points 34 and 36, release of handle 80 will permit spring 89 to seat the brakes to lock further rotation of screw 40 thereby restraining axial movement of nut 36 along screw 40. The adjustor is once again in holding position.

Another form of the adjuster is shown in FIGURE 5. This disclosure employs much the same arrangement, deviating for the most part in the brake mechanism.

An elongate tubular casing 126 has a pair of open ends, and intermediate thereof two sets of pins 101 and 103 serving to anchor first and second thrust-bearing blocks 105 and 107 respectively therein. One set of the pins, preferably set 101, may additionally serve as a means to anchor casing 126 to a bed or chair frame which is to be adjusted.

An elongate tubular member 132 is concentrically positioned and axially slidable within casing 126 and has provided at its outer end an attachment means, which as shown is a pair of holes 109. The other of inner end of member 132 fixedly contains a nut member 138 of the type described for use with the disclosure of FIGURE 3. A screw member 140 containing helical threads of appreciable lead over a major portion of its length is received within nut 13S. Screw member 140 terminates in a portion 142 of reduced diameter at its left or inner end portion, and the other end has attached thereto an annular bushing 143 slidable within the member 132. This bushing serves the purpose of concentrically positioning the screw within member 132. The left end of portion 142 has a further reduced portion 142' which serves in mating and sliding relationship with an axial recess 135' in shaft 135 for bearing purposes. The second bearing block 157 of annular form having a hole 111 axially therethrough forms the backing to support a pair of thrust bearings 113, 115 on either side thereof. Cooperating with the thrust bearings 113, 115 and surrounding the reduced portion 142 of screw 14% is a pair of thrust sleeves 117, 117' each having annular flanges 119 extending outwardly in abutting relation with opposite ends of thrust bearings 113, 115 to restrain the bearings in position adjacent either side of block 107. Thrust block 1117 provides a backing for bearings 113, 115 which are secured in position on shaft 142 to restrain axial movement of screw 14d which extends therethrough. A brake sleeve 123 axially abuts one end of the sleeve 117 and has an annular brake flange 125 radially extending therefrom. A nut 127 threaded on threaded portion 12? serves to maintain the three sleeves in fixed alignment on portion 142 of screw 140.

Insofar as described, screw 14%) is free for rotary movement. The mechanism which controls the braking of screw 140 will now be described. Thrust-bearing block 1135, having an axial opening 131 therethrough, is concentrically positioned within casing 126 and is fixed within the cylindrical sleeve 133 by means of pins 101. Opening 131 in block 105 loosely receives the shaft 135 coaxial with screw 1413. Shaft 135 has a radially disposed handle 137 rigidly attached at its outer end 13%. The inner end of shaft 135 supports a cup-shaped member 141 surrounding nut 127, but not in contact therewith. A brake material 143 of annular form is bonded or otherwise secured to the open end of cup 141 in contact with flange 125 on sleeve 123. Shaft 135 supports a flange 144 adjacent the base of cup 141, as can be seen in FIGURE 5, which serves to limit axial movement of shaft 135 to the left whenever flange 144 abuts thrust block 1%", a space normally being provided therebetween. Cylindrical sleeve 133 is concentrically received within casing 126 and is axially movable therein within the limits of a pair of diametrically opposed slots 151 through which aforementioned pins 101 extend. A sleeve or bearing 136 surrounds each pin 1111 and is positioned within slots 151. It is apparent that sleeve 133 is free to move only a limited axial distance in either direction relative to the bearing block 105. The left end portion of sleeve 133 is internally threaded to securely receive therein thrust nut 134 loosely journalling a smaller diameter portion 153 of shaft 135 therethrough. The inner end of sleeve 133 is provided with an inturned annular flange 155 extending beyond and overlapping in an axial direction the annular brake flange 125. Bonded or otherwise secured to the inner axial face of inturned flange 155 is a brake material 146 lying adjacent with a face of annular flange 125 for frictional engagement therewith.

Sleeve 133 contains a pair of diametral slots spaced axially from slots 151. A cam member 145 loosely sur rounds shaft 135 for limited relative axial movement thereon. A pair of pins 149 extend radially from cam member 145 through slots 157, thereby permitting limited axial movement of member 145 relative to sleeve 133 without permitting relative rotation between cam member 145 and sleeve 133. Cam 145 has a pair of inclined axial surfaces 147, 147'.

Sleeve 133 is mounted for a limited amount of axial movement relative to casing 126 and block 105. A pin 1551, shorter than the internal diameter of sleeve 133, extends diametrically through shaft 135. Pin 150, as illustrated best in FIGURE 5, is positioned in the trough between axial surfaces 147, 147 of cam member 145.

Plural axially aligned Belleville springs 161 surround reduced diameter 153 of shaft 135 and bear axially against annular shoulder 162 of said shaft 135 and against thrust bearing 159. Pin 150 is normally urged to the right into contact with cam member 145. It can be seen, with spring 161 so positioned, that the normal reaction of the forces is to urge shaft 135, flange 144, and cup 141 to the right against the brake flange and at the same time urge bearing 134, sleeve 133 and flange 155 to the left so that flange 155 engages brake flange 125 from the side opposite to cup 141. In this way the screw 1413 is prevented from rotating in either direction.

It can be seen that flange 125 is resiliently held between spring-pressed brake surfaces 143, 146. It is apparent then that screw shaft 140 will be restrained from freely turning in bearings 113, 115.

The Believille spring 161 biases brake surfaces 143, 146 into contact with flange 125 to restrain rotation of screw 141). Even when an appreciable axial force is applied to the screw, a holding force is encountered by surfaces 143 or 146. The floating arrangement of the braking elements provides an equalization of forces on the brake surfaces, and assures brake contact and self energization.

A pin 163 on screw member 141) determines the extent of travel of nut 133 along the screw in one direction, and flange 119 determines the extent of travel in the other direction.

In operation, the distances between points 101 and 1G9 are manually adjustable upon pivotal movement of a handle 137 to release the brake and are fixedly braked upon release of the handle.

Assuming the adjustor to be in a normally braked position, means 1111 and 1119, to which a bed frame attachment is made, are held at a fixed distance apart. The brake surfaces 143, 146 are urged by springs 161 into holding contact with flange 125 of sleeve 123, which in turn is secured with shaft portion 142 of screw 140, preventing the screw from turning. A longitudinal pull, for instance, on member 132 would not result in nut 138 moving along screw 144?.

Whenever it is desirable to adjust the position of the bed, on which this unit is installed, it is only necessary to pivot shaft a few degrees in either direction by moving handle 137. As pin 150 is pivoted, it bears against surfaces 147, 147 of cam 145. The pins 149 engage the edge of opening 157 and the spring 161 is compressed whereupon sleeve 133 is moved to the right and shaft 135 is moved to the left, whereby braking surfaces 143, 146 are moved in an opposite direction away from flange 125 to effect release therefrom. Screw is now free for rotation in either direction. Body pres sure against the bed frame will urge means 101, 199 toward or away from each other. Screw 140 will be rotated under an axial force applied to nut 138. Whenever the desired position is attained, release of the handle 137 will permit Belleville springs 161 to seat brake surfaces 143 and 146 against flange 125 to prevent further rotation of screw 141 Further forces tending to compress or extend member 132 within casing 126 will be resisted.

The brake mechanism is normally urged to restrain the first and second positionable member at a predetermined axial relationship. Upon manual release of the brake mechanism, the first and second members can be axially retracted or extended to a new position whereupon release of the brake will permit it to seat by spring action and fixedly restrain the members in the new position.

Having thus described my invention, it is obvious that various modifications may be made in the same without departing from the spirit of the invention; and, therefore, I do not wish to be understood as limiting myself to the exact forms, constructions, arrangements and combinations of parts herein shown and described.

I claim:

1. A position brake mechanism comprising in combination; a first member and a second member coaxially and telescopically disposed with respect to each other, means on each member for connection to a device to be positioned, said first member fixedly carrying a nut means therewith, said second member rotatably carrying a screw means having helical threads of appreciable axial lead cooperating with the nut means whereby axial force applied between said members will cause relative axial movement therebetween and rotation of said rotatable screw, and brake means on said second member movable to brake the screw means for nonrotation in either direction to thereby prevent relative movement of said members.

2. A position brake mechanism comprising in combination; a first memberconcentrically received in and coaxially disposed with respect to a second member and adapted for relative axial movement therein, means on each member for connection to a member which is to be maintained in relative position, said first member fixedly carrying a nut means at one end thereof spaced apart from said connection means, said second member rotatably carrying an elongate screw means axially fixed therewith, said screw having helical threads of appreciable axial lead cooperation With the nut means, brake means on said second member normally urged by resilient means into braking contact with the screw means to prevent rotation thereof, whereby an axial force applied to said members in either direction through the connection means is restrained from causing rotation of the screw and relative axial displacement between the members, and a brake release means operative with the brake means on said second member to move the brake means out of contact with the screw means whereby an axial force applied to said members in either direction through the connection means causes rotation of the screw means and relative axial displacement of said members.

3. A position brake mechanism comprising in combination; a first elongate member adapted to be axially slidably and telescopically received within a second elongate member, connection means located at one end of the first member for connection to a first part to be held in a relative position, and a nut means contained near the other end of the first member in fixed relation therewith, second connection means located on the second elongate member for connection with a second part to be held in a fixed position relative to the first part, an elongate screw means rotatably mounted in axial alignment within the second member and cooperatively received by the nut means, said screw means containing helical threads of appreciable axial lead whereby relative linear force and movement applied to the first and second members causes rotation of the screw means within the sec ond member, plural axially disposed axially urged braking means adapted for cooperation with the screw means to restrain rotation of the screw in either direction where- 'by the nut and screw are restrained from relative axial movement and whereby the first and second connection means are fixed at a predetermined relative axial extent, and brake release means operative to release the screw means for rotation and repositioning of the first and second members.

4. A position-holding mechanism comprising in combination: a pair of telescopically disposed tubular members adapted to be connected to respective members which are to be fixedly retained in one of a plurality of positions, one of the tubular members rotatably carrying elongate screw means having relatively steep threads, the other of said tubular members fixedly carrying nut means receiving the rotatable screw means for relative rotational and longitudinal movement therealong upon an axial force being applied to the tubular members tending to move them in opposite directions, said screw means having annular means thereon adapted to be received in axial gripping engagement, said gripping means comprising a third tubular member telescopically received within the one tubular member and having a frictional surface disposed adjacent the annular means for engagement therewith, resilient means adapted to urge the frictional surface into gripping engagement with the annular means to thereby prevent rotation of the screw in either direction, and means manipulatable to overcome the resilient means and move the third tubular member axially to thereby release said gripping engagement whereby the screw and nut means are free for relative rotational and axial movement as an axially directed force is applied between said pair of members.

5. The structure of claim 4 wherein the manipulatable means comprises a rotatable shaft concentrically disposed within the one tubular member and provided with axially facing cam means disposed upon rotation of the shaft to move the third tubular member axially.

6. The structure of claim 5 wherein the cam means are radially disposed.

7. The structure of claim 4 wherein the gripping means comprises a pair of concentrically disposed tubular members each having annular shoulders adapted to be resiliently urged into engagement with the annular means on the screw member from either side thereof.

8. A position-retaining device comprising in combination: a pair of telescopically disposed tubular members having portions thereof adapted to be connected to respective members which are to be retained in a desired relatively fixed position, one of the tubular members having an elongate screw means rotatably mounted therein, the other of the tubular members having a fixedly mounted nut means operatively receiving the screw means, said tubular members and the nut and screw means being coaxially disposed, said screw means having an annular portion fixed thereon, a second pair of telescopically disposed tubular members each having annular friction shoes disposed adjacent the screw annular portion, resilient means adapted to urge the shoes into opposed gripping engagement with the screw annular portion to preent rotation of the screw in either direction and relative linear movement of the first pair of tubular members, said screw and nut means provided with relatively steep threads, and release means operable to overcome said resilient means whereby the screw means are free for rotation in either direction whereby an axially directed force applied between said first pair of members causes said nut and screw to move relative to each other and permit the first pair of members to be positioned in another relative position and' there retained upon repositioning the release means.

Hogan et al. Aug. 19, 1958 Ochtman Oct. 28, 1958 

1. A POSITION BRAKE MECHANISM COMPRISING IN COMBINATION; A FIRST MEMBER AND A SECOND MEMBER COAXIALLY AND TELESCOPICALLY DISPOSED WITH RESPECT TO EACH OTHER, MEANS ON EACH MEMBER FOR CONNECTION TO A DEVICE TO BE POSITIONED, SAID FIRST MEMBER FIXEDLY CARRYING A NUT MEANS THEREWITH, SAID SECOND MEMBER ROTATABLY CARRYING A SCREW MEANS HAVING HELICAL THREADS OF APPRECIABLE AXIAL LEAD COOPERATING WITH THE NUT MEANS WHEREBY AXIAL FORCE APPLIED BETWEEN SAID MEMBERS WILL CAUSE RELATIVE AXIAL MOVEMENT THEREBETWEEN AND ROTATION OF SAID ROTATABLE SCREW, AND BRAKE MEANS ON SAID SECOND MEMBER MOVABLE TO BRAKE THE SCREW MEANS FOR NONROTATION IN EITHER DIRECTION TO THEREBY PREVENT RELATIVE MOVEMENT OF SAID MEMBERS. 